Safety apparatus for high pressure liquid jet system

Abstract

A safety apparatus for use in a hydrocutting or hydroblasting system which has a normally closed shutoff valve for coupling a high pressure water source to a hydrocutting or hydroblasting gun. The shutoff valve is controlled by a solenoid valve coupled between an air-to-open (ATO) input of the shutoff valve and an air power source. A normally open inductive proximity switch, through a relay circuit, provides a control signal to the solenoid valve. The inductive proximity switch is located near a cutting or cleaning nozzle of the gun. When the inductive proximity switch comes in close proximity of a metal object to be cleaned or cut, the proximity switch closes, thereby opening the solenoid valve and the shutoff valve. When the gun is removed from the physical proximity of the metal, the inductive proximity switch opens, thereby turning off the shutoff valve.

What is claimed is: 
     
       1. A safety apparatus for use in a high pressure fluid jet system for operation by an operator, said fluid jet system includes a high pressure fluid source for supplying fluid, a nozzle for ejecting said fluid, and an electrically operated valve having an on-off flowthrough path, said flowthrough path coupled between said high pressure fluid source and said nozzle, said safety apparatus comprising: a trigger switch operable by the operator of the high pressure fluid jet system and   a proximity switch located near the nozzle for indicating when said proximity switch is within a first distance of a structure to be operated on by the high pressure fluid jet system,   said trigger switch and said proximity switch connected to the valve to operate the valve when said trigger switch is operated by the operator and said proximity switch indicates proximity to the structure at a concurrent time.   
     
     
       2. The safety apparatus of claim 1, wherein said proximity switch is an inductive proximity switch. 
     
     
       3. The safety apparatus of claim 1, wherein said first distance is 40 millimeters. 
     
     
       4. The safety apparatus of claim 1, wherein said proximity switch indicates when said proximity switch is within said first distance of said structure when said structure is a metallic structure. 
     
     
       5. The safety apparatus of claim 1, wherein after said valve is operational said trigger switch sustains operation of said valve as long as said trigger switch is operated by the operator. 
     
     
       6. The safety apparatus of claim 1, wherein the operation of said valve includes turning on the flowthrough path of said valve. 
     
     
       7. A safety apparatus for use in a high pressure fluid jet system for operation by an operator, said fluid jet system includes a high pressure fluid source for supplying fluid, a nozzle for ejecting said fluid, and an electrically operated valve having an on-off flowthrough path, said flowthrough path coupled between said high pressure fluid source and said nozzle, said safety apparatus comprising: a trigger switch operable by the operator of the high pressure fluid jet system and   an inductive proximity switch located near the nozzle for indicating when said proximity switch is within a first distance of a structure to be operated on by the high pressure fluid jet system,   said trigger switch and said proximity switch connected to the valve to operate the valve when said trigger switch is operated by the operator and said proximity switch indicates proximity to the structure at a concurrent time.   
     
     
       8. The safety apparatus of claim 7, wherein said first distance is 40 millimeters. 
     
     
       9. The safety apparatus of claim 7, wherein said proximity switch indicates when said proximity switch is within said first distance of said structure when said structure is a metallic structure. 
     
     
       10. The safety apparatus of claim 7, wherein after said valve is operational said trigger switch sustains operation of said valve as long as said trigger switch is operated by the operator. 
     
     
       11. The safety apparatus of claim 7, wherein the operation of said valve includes turning on the flowthrough path of said valve. 
     
     
       12. A high pressure fluid jet system for operation by an operator, said fluid jet system comprising: a high pressure fluid source for supplying fluid;   a nozzle for ejecting said fluid;   an electrically operated valve having an on-off flowthrough path, said flowthrough path coupled between said high pressure fluid source and said nozzle; and   a safety apparatus comprising: a trigger switch operable by the operator of the high pressure fluid jet system; and   a proximity switch located near the nozzle for indicating when said proximity switch is within a first distance of a structure to be operated on by the high pressure fluid jet system,   wherein said trigger switch and said proximity switch are connected to the valve to operate the valve when said trigger switch is operated by the operator and said proximity switch indicates proximity to the structure at a concurrent time.     
     
     
       13. The fluid jet system of claims 12, wherein said proximity switch is an inductive proximity switch. 
     
     
       14. The fluid jet system of claims 12, wherein said first distance is 40 millimeters. 
     
     
       15. The fluid jet system of claims 12, wherein said proximity switch indicates when said proximity switch is within said first distance of said structure when said structure is a metallic structure. 
     
     
       16. The fluid jet system of claims 12, wherein after said valve is operational said trigger switch sustains operation of said valve as long as said trigger switch is operated by the operator. 
     
     
       17. The fluid jet system of claims 12, wherein the operation of said valve includes turning on the flowthrough path of said valve.